Liked especially the amplitude to emit gravitons, formula 16.3.4, page 214, and 16.3.5, page 214, the probability of a graviton emission per disintegration. In these two examples, Feynman linked an allegedly abstract particle, the 'quantum' graviton, with particle decay phenomenology. This is the strength of this volume. I.e. exact calculations. The negative, if you can call it that, is that Feynman has no coverage of the CMBR in this book. I.e. he COULD NOT POSSIBLY know of it. The book is dated, badly dated, in parts, while other calculations interrelate with amazingly contemporary issues. I.e., if one picks and chooses, many of the calculations are very contemporary in terms of what they say, albeit, that Feynman did ALL of this with NO knowledge of contemporary cosmology. and Inflation.
My gripe is that some of the ideas are old hat, but others are still amazingly pertinent. In all, considering the year, i.e. this 50 year old reference is a gem.